In the baling arts, the bale tying technique using preformed wire ties having "shepherd's hooks" on the ends thereof was disclosed as early as 1965 in U.S. Pat. No. 3,168,912. There have been numerous attempts at automating the laborious and time consuming job of connecting the bale ties including the device disclosed by Trumbo in U.S. Pat. No. 3,863,558 and by Jaenson in U.S. Pat. No. 4,484,518. The teachings of U.S. Pat. No. 4,484,518 are incorporated herein by reference.
In an apparatus built in accordance with the '518 patent, it is critical that the follow block of the associated baler be properly positioned for the tying of the wire about the bale to be successful. That is to say, the follow block must be held within close limits in both horizontal directions with follow block guides that wear and require frequent shimming.
Vertically, the follow block must come to a closely controlled, fixed shut height for the wires to successfully tie. Fixed shut height presses are undesirable because lighter weight bales expand more than heavy bales when the ties are removed; thus, in the textile mills, the opening room machinery that plucks the top surfaces of the bales will feed less weight of fiber from the lighter bales thereby causing undesirable variations in the bale blends.
In addition, the '518 patent requires the geometry of the wire bending systems near the ends of the wire to form a sharp bend in the wire to cause the wire ends to push forward of the initial loop positioning device on the load side, and to ensure that both wire ends entering the bottom follow block are horizontal as the wire loops engage, and also, to be able to push the wire loop ends together to make the knot without the bend in the wire yielding. This required action has two major drawbacks. First, the geometry of the bending motion requires that the wires slide along the bending mechanism surfaces. This requires wear resistant surfaces to be added to the bending fingers. Secondly, the sharp bends in the wire cause the wire to be longer than necessary to surround a given size bale under final compression in the press.
In our apparatus we provide geometry for the wire bending systems near the outer ends of the wire that form a gentle bend that results in no relative longitudinal motion of the wire and the bending fingers. This geometry requires that the center of the bending finger shafts be near the center line of the wires when the wires are initially loaded. To accomplish this we provide notches in the bending finger shaft in each wire position. Our wire bending system then first eliminates the wear of the sliding contact of the wire with the bending fingers of patent '518. Secondly, our system allows the gentle curve of the wire to more closely adhere to the lower edges of the bale, thus saving wire length. To further take advantage of the gentle curve formed by our bending system at the lower edges of the bale, we provide tapering surfaces at the outer ends of the bottom follow block platen bars to allow the bend of the wire to pass up into the wire slots in the platen as the wires come together in final knotting position.
Also, the joining of the wires in the prior art device disclosed in the '518 patent is obscured by the bale and since the bottom platen must be raised to make a connection and any modification to the interior surfaces of the wire tie guides in the follow block require dismantling of the follow block by loosening a set of connecting bolts. The bolts are a source of considerable down time inasmuch as they weaken or loosen under stress. Accordingly, there is a need for a more efficient, more reliable, and more easily maintained automated bale tying apparatus.